One of the principal challenges in operating a restaurant is to provide rapid and high volume service to customers, yet minimize waste of food. Efficient use of time, space and energy are vitally important to success. Present methods of restaurant food preparation include prior preparation, then the placement of the prepared food under infra-red lamps or other sources of radiant heat to maintain the food at the desired temperature. Another method involves the use of a food warmer, most often a rectangular tank open at the top, with an inside chamber and a heating element mounted in the tank for heating water located in the chamber. Food can be placed directly in the chamber. When water is used, food is placed in trays or bowls resting at the top of the tank and extending downward into the chamber. Food in the trays or bowls is heated mainly due to conduction.
In the above methods, canned food is removed from the can prior to heating. This results in waste for a number of reasons. Settling and separation of some foods while stored in tin cans causes an unsightly deposit inside the can which is often discarded though it may be as nutritious as the remainder of food in the can. In other cases, properly mixed food nonetheless adheres in part to the can inside surface and is discarded along with the can. Most waste probably results from the practice in restaurants of removing the food from the can prior to heating. Frequently partially or totally unused food must be discarded since the can has been opened. The temptation to save and use such food, despite regulations and ordinances to the contrary, potentially worsens sanitary conditions in the restaurant.